Teeming ingot-mold



E. GATHMANN.

TEEMING INGOT MOLD. APPLICATION FILED-NOV. 4.1919.

H Patented Mar. 9, 1920.

Z5772] gaihmamv Baltimore cit-y, Maryland,

EMIL oacrmvumiv,- or BALTIMORE, MARYL-AN-D.

TEEMIN G INGOT-MOLD.

Application filed November 4, 1919. Serial No. 335,581.

To all whom it may concern:

Be it known that I, EMIL GATHMANN, a citizen of the United States, residing in have invented certain new and useful Improvements in Teeming Ingot-Molds, of which the following is a specification.

My present invention relates generally to the molding ofsteel ingots and more particularly to the casting of ingots of effervescing, gassy or so called unkilled steel such as is commonly used in making boiler, tank and ship plates,,steel pipes and other plates or articles of low carbon steel, standard shapes and similar products.

Steel may broadly be separated into two divisions, namely, eifervescing or gassy steel, also termed evolution steel and nonefi'ervescing or killed steel and also termed solution steel.

Unkilled or efi'ervesc-ing steel contains a very large volume of gases which are evolved while the metal is being teemed from the ladle nozzle into the mold and while the temperature of the steel is being reduced prior to the solidification or freezing of the steel. These gases consist principally of hydrogen, carbon monoxid and nitrogen and ammonia. It is generally understood that the hydrogen gases are first evolved and form the, at times, troublesome skin blow holes in the forming ingot.

Metallic ingot molds are teemed ordinarily either, by what is termed by those skilled in the art, top casting or by a method known as bottom casting. According to my invention I combine these two methods by top casting one ingot and bottom casting another, the molds in which the ingots are cast being connected by .a novel runner or inclosed channel through which the molten metal passes from mold to mold.

In killed steel, gases are mostly retained in the steel in solution or combined with an oxidand, being lighter than the liquid steel, pass to the top of the ingot in the form of a solid slag or like material and the killed steel ingot does not, if suitably killed, have any blow holes. The difference in volume between the liquid and solid steel, is

' characterized by a pipe or shrinkage cavity,

means for lessening which have been heretofore devised as described in patents heretofore granted to me and to others.

In suitable efi'ervesoing steel piping does not occur but a combination of three types Specification of Letters Patent.

Patented Mar. 9, 1920.

of blow holes are apt to be formed unless the ingot is correctly molded and teemed. These consist of what are called skin blow holes at or near the outer surface of the ingot; intermediate holes, called deep-seated holes, between the outer zone or skin and the central portion of the ingot; central holes located at random in the central portion'of the ingot.

Skin holes are very undesirable and constitute serious defects in the ingot. Intermediate and deep-seated holes are, however, not considered harmful as they are for the most part welded or semi-welded and do not detract from the quality of the product where elfervescing steel is mostly used in which product surface quality or smoothness is of primary importance.

In methods of bottom casting ingots previously used the apparatus has been quite expensive and cumbersome to use and in the methods previously used in top casting and bottom casting an adjoining ingot difficulties have been encountered in obtain ing a full and uninterrupted flow of metal from one mold to another unless the stool on which-the molds rest was made entirely of refractory or poor heat-conducting material. Such a stool construction is very expensive and also unsatisfactory because in such practice the entire lower portion of the ingot will remain liquid for a longer period 7 than the portion immediately above it, and thus cracks and tears are formed in the surface of the ingot due to differences in shrinkage volume.

According to my invention, I construct the runner or channel connecting the two molds in such way as to materially decrease the cost of construction and at the same time prevent differential shrinkage in the lower part of the ingot caused by marked variation of the skin solidification at this portion of the ingot compared with that part of the ingot immediately above it. I do, however, retain the steel in a liquid condition in the ingot in its interior or central portion for a longer period at the'lower part of the ingot at or near the mouth of the channel which connects the two molds. This is an important feature in obtainin uniform height for top or bottom cast ingot-s. If the mouth of the channel werelevel with the bottom of the ingot the freezing steel on the relatively cold metallic stool would form bulges or fins over the mouth of the V "i: channel and prevent the proper passage of' metal through the channel and at times the metallic stool or base B.

to the other.

channel would be closed or shut off thus preventing the flow of metal from one mold I have found that when the mouth of the channel -is raised above the stool such troubles are not encountered as the steel maintained longer in a liquid state on this level.

These and other features of my invention fully described.

metallic molds A, A for use in casting in-Y gets, from efi'ervescing steel resting on a This stool or base is formed with a recess an adapted to receive runners, or blocks made of refractory brick vvided with a material and containing channels through which thelower portions of the two molds communicate. Preferably sections, C, C which are seated in the recess 00 and held therein in any suitable way, as by fire clay I applied in the manner indicated.

The sections C, C are of substantially the same size and shape, being thus interferent shape. Each section C or C comwhich lies in vertical portion 0 which extends into the mold. Each runner. section C, C is prochannel 3 which extends horizontally from one end of the section nearly to its opposite end and then extends upwardly throug'h'the raised portion 0 The upper portion of the channel being flared or widened, as indicated, to form amouth 0 for the reception or for the delivery of the liquid metal. The inner ends of the section C, C are fitted to the mold section 0 in any suitable way, indicated in the drawings.

The top casting mold A may be poured or teemed in any suitable way. I have shown a portion of a ladle nozzle D for this pur ose, details ofwhich need not be descr'i ed. Steel delivered from the nozzle passes first into the mold A, then throu' h the channel into the bottom of the mold E.

The liquid metal forming the ingot being cast in the mold A must rise above the top of the mouth of the channel in said mold risen to gots have the runners are made in three is of a difpreferably in the manner dinal section of the ingots sh diagrammatic only and illusbefore any metal can pass through'the channel into the mold A. When the metal has this extent in the mold A a constant equilibrium of metal or approximately such willb'e established and maintained in the two molds and the metal in the mold A will rise orgrow the amount of metal delivered by the ladle to the mold A, being approximately one half such amount if the two molds are of equal cross section. V

The two ingots during formation or teeming are always of approximately the same height or rate of growth in the two molds and when teeming is completed and the insolidified the latter will appear approximately as shown in the drawings, being then of approximately the same height and of similar physical structure."

By thus teeming the ingots the surfa'ce or skin blow holes in the major portion of the ingot are prevented. It must be borne in mind that the steel begins to freeze almost'as soon as it comes in contact'with any part of the mold a d that hydrogen gases are evolved upon the lowering of temperature. If there is not suflicient movement or action in the forming ingot at this time to wash according to p them away these gases will form bubbles or blow holes near the skin of the ingot which makes that portion of the ingot unfit for use as the bubbles or blow holes when located near the skin are only' covered by a thin wall of steel and will open up to the atmosphere and become oxidized during reheating of the ingot and during the rolling or fabricating operation when blooms or lates' are being produced. In this way deects such as tears, pit seams and scabs are fomneds These defects or skin. blow holes produced inthe ordinary top casting. of eifervescing steel are more apt to form in thelower portion of the ingot than in the. upper portion thereof as there is less churning or motion of the steel in the lower half of a top cast ingot than in the upper part thereof and consequently less washing action is produced on the forming skin. This is not the case when the ingot is properly bottom cast as there is then more motion or churning in the lower portion of the ingot therefore skin blow holes are practically eliminated. i

The blow hole formation in the longituown in the drawings .is trates a type of blowholes which is often desired or at any rate considered harmless When, however, one

if eflervescing steel for making products of the kind before mentioned is used. Such blow holes are deeper seated and are formed after the completion of the teeming operation. Theblow holes shown at the lowermost portion of the ingot in contact with the metallic stool are, however, skin blow holes and are apt to open up after reheating and rolling but'these blow holes occur in a part of the ingot which is generally discarded or sheared off from the bloom or slab during rolling. It is also common to shear off the upper portion of the ingot which also has blow holes that are dangerously near the skin or surface of the casting. The recessed portions 0 of the runner sections C, C in which the mouths ofthe channels are located, should extend sufficiently far above the top of the stool to clear the metal undergoing a preliminary freezing on the stool in the lower part of the mold while the mold is being teemed. The runner sections C, C, C are preferably made of tire brick or other refractory material capable of withstanding the necessary handling to place them in position and the heat of the molten metal entering the mold without serious cracking or fusing.

The runner sections are preferably held in place by fire clay I) applied in the manner indicated and they are also held down against the floating action of the mold by a portion of the molds which rest upon .them. Vhile I have shown two molds associated for top and bottom casting it should be understood that a larger number of molds may be thus associated.

I find the best results are obtained by extending the inner ends of the runner sections to a considerable extent above the bottom of the molds and in making the mouths of the channel of considerably greater diameter than the channel itself.

Inasmuch as I am apparently the first to bottom cast an ingot by metal taken from the lower portion of another ingot in a plane.

above its extreme lower end my invention involves a new method of operation which is hereinafter claimed.

I claim as my invention 1. A plurality of metallic ingot molds adapted for top and bottom casting, a top casting mold being connected with a bottom casting mold by a runner extending from mold to mold and having at its receiving.

end a recessed portion extending vertically into the mold chamber to a level materially above the bottom wall of the mold.

" 2. A plurality of metallic ingot molds adapted for top and bottom casting, a top casting mold being connected with a bottom casting mold by a runner extending from mold to mold and having at its receiving and delivery ends recessed portions extending vertically into the mold chambers to levels materially above the bottom walls of the mold.

3. A plurality of metallic lngot molds adapted for top and bottom casting and having chambers, the longitudinal axes of which are substantially ertical, a top casting mold being connected with a bottom casting mold by a runner extending from mold to mold and having atits receiving end a recessed portion with a. flared or widened mouth extending into the mold chamber to a level materially above the bottom wall of the mold.

l. A plurality of metallic ingot molds adapted for top and bottom casting, a. top casting mold being connected with a bottom casting mold by a runner extending from mold to mold and having at its receiving end a recessed portion extending upwardly into the mold chamber to a level materially above the bottom of the mold, said level being above'the top of the stool where the metal first freezes during the teeming operation.

A plurality of metallic'ingot molds adapted for top and bottom casting and which rest on a metallic stool having a recess in its upper surface, and which molds are connected by a runner composed of sections of refractory material seated in; the recess of the stool and extendingfrom mold to mold, the receiving end of said runner having a recessed portion extending into a mold chamber to a level materially above the top surface of the stool or the bottomof the mold. x r

6. A metallic mold adapted for bottom casting, having a. mold chamber, the longitudinal axis of which is substantially vertical,

a recessed metallic stool on which the mold is supported, a rumier in said stool composed of sections of refractory material seated in said recess, the delivery end of which runner has amouth portion extending upwardly into the mold chamber to a level above the bottom of said chamber and materially above the top of the stool, which stool provides a bottom closure for the mold chamber where the liquid metal forming the ingot first freezes during the teeming operation.

7. A metallic mold adapted for bottom pouring, having a mold chamber, the longitudinal axis of which is substantially vertical, a recessed metallic stool, a runner composed of sections of refractory material seat-- ed in said recess, the upper surface of which stool is arranged in a substantially horizontal plane, and the delivery end of the runner having a recessed portion with a flared or widened mouth extending up into the mold chamber to a level above the bottom of said chamber and materially above the top of the stool, said stool providing'a bottom closure for the chamber where the liquid metal forming the ingot first freezes during the teeming operation.

8. The method hereinbefore described of top and bottom casting, which consists in teeming one mold at the top and in drawing molten metal approximately vertically through the base of said top-teemed mold at a level considerably above the base of the mold and above the base or bottom of the ingotbeing formed therein, and transferring it to the lower portion of another mold which is thus bottom-teemed.

9. The method hereinbefore described of top and bottom casting in two adjoining molds the base'portions of which communicate with eachpther, which consists in teemingfor top casting one of the molds and in drawing molten metal centrally through the base portion of said top casting mold at a level appreciably above the bottom of said mold and above the base or bottom of the ingot being formed therein, and in transto the base ferning the metal thus drawn portion of the other mold.

' In testimony whereof I have hereunto sub 7 scribed my name.

EMIL GATHMANN." 

